1. Field of the Invention
The present invention relates to a technology for performing auto-focusing using face detection information.
2. Description of the Related Art
Conventionally, when photographing an object image with an auto-focus camera in which the focus detection area is fixed in the middle of the frame, it has been necessary to place the object image in the center, engage the focus lock, and then compose the photograph.
A method has therefore been developed for setting a plurality of focus detection areas inside the frame with the object of making auto-focus possible without changing the composition of the photograph, namely, without using the focus lock. This technology has two methods, one for the user to select one desired focus detection area from a plurality of detection areas, and one for estimating the main object from focus detection results from the plurality of focus detection areas and determining the focal length to use. Of these, the latter method has greater convenience, as the user can photograph without worrying about selecting a focus detection area. However, it has the problem that the automatically selected focus detection area does not necessarily detect the focus for the object which the user wishes to photograph.
One means of solving this is an image capturing apparatus constituted so as to detect a person's face in image data, set a focus detection area so as to include the detected face, and adjust the focus accordingly, in order to refine the precision of the estimation discussed above by limiting to humans. (See Japanese Patent Application Laid-Open No. 2003-107335.) Japanese Patent Application Laid-Open No. 2003-107335 describes an image capturing apparatus constituted so as to detect an object's face in image data, set a focus detection area so as to include the detected face, and adjust the focus accordingly, in order to refine the precision of the estimation discussed above by limiting to the faces of objects. In Japanese Patent Application Laid-Open No. 2003-107335, the focusing action is performed using a detected face, so the possibility of mistakenly focusing on other objects decreases.
However, with Japanese Patent Application Laid-Open No. 2003-107335, focus can sometimes be unadjusted in cases where the contrast of the face is low and sufficient focus detection data cannot be obtained, even though the face can be detected. Also, if objects such as flower vases at differing distances in the focus detection area are closer to the image capturing apparatus than a face, focus cannot be adjusted, even though a face can be detected.